What a simple question with enormous implications! I like the way you find yourself evaluating expectations as catalysts for angry (hateful) reactions.

Humans are very lovable. Behold any newborn or toddler before the gauntlet of abuse begins. The same applies to animals except they are spared abuse by their own kind and only become ugly, as with our kind, when they too are abused.

So, I think it can be more accurately put that we don't so much hate other people as we do their conduct when it doesn't measure up to our expectations; when it doesn't exemplify our personal values.

Both cure and prevention, sadly, are out of reach. What to do, what to do?

another thing that helps me not to hate is remembering that everyone is just doing the best they can with what they have learned so far. we all have different experiences- even in the same family. I grew up in a violent household. My brother chose the darkness and is serving out a life sentence in prison. I grew up right next to him. I have 20 years of sobriety and work serving others, my life is simple , but good. I have never intentionally harmed anyone like he did. Everything we are is a choice.

"When you change the way you look at things, the things you look at change". ~Wayne Dyer
It is sometimes a huge challenge to see the good, if you are feeling like crap. I sometimes have to pretend kindness when I automatically want to spew venom. But I have noticed that when I smile, a lot of folks will smile back- not everyone- and we should not expect them too. A big part of disappointment in others is having expectations. If you come into a room expecting high fives, you will be pissed off when you are ignored. Walk in expecting nothing, and carrying an intention to be kind, and you will find kindness.

Yeah but here being polite helping others is more common it's why I moved here 18 years ago came from city where miserable people are more common

Ha. I hate people right now. My duplex neighbor moved out into the early hours of morning, causing my dog to bark. I just let her.
They were making all kinds of racket. Went out this morning—AFTER the trash had run—to find the skanky bitch had filled MY bin(which had one bag only) but not bothered to put it on the curb, plus added items that won’t be collected.
So I took those and put them in her pile and later I’ll switch her empty bin for my full one. Since it’s another week to trash day!

I see a lot of what you're talking about....and then - someone will hold a door open for me or just strike up a friendly conversation for no reason at all. It's a mixed bag - but I suspect that if you are in an environment where people are "doing their jobs" - their moods are probably pretty sour - (especially the folks who work in retail) because in spite of what we hear about our "booming economy" - most people are still struggling to make ends meet. That day after day struggle will really bring you down ....I try to keep that in mind when I'm faced with the rude encounters.